Reverse system for water-jet propulsion personal watercraft

ABSTRACT

A reverse system of a water-jet propulsion personal watercraft is disclosed. The reverse system typically includes a water jet pump configured to propel the watercraft, a reverse bucket disposed rearward of the water jet pump to be vertically pivotable and configured to receive water ejected rearward from the water jet pump and to direct the water substantially forward, and a pump cover configured to cover the water jet pump from below. The pump cover typically includes a restricting portion, and the reverse bucket typically includes a stopper. The restricting portion and the stopper typically are configured to contact each other to restrict upward pivot movement or downward pivot movement of the reverse bucket within a predetermined range.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reverse system configured to move a water-jet propulsion personal watercraft rearward.

2. Description of the Related Art

In recent years, water-jet propulsion personal watercraft have been widely used in leisure, sport, rescue activities, and the like. The personal watercraft is configured to accommodate an engine within a body formed by a hull and a deck covering the hull from above. The engine is configured to drive a water jet pump, which pressurizes and accelerates water sucked from a water intake generally provided on a hull bottom surface and ejects it rearward from an outlet port. Thereby, the personal watercraft is propelled.

In water-jet propulsion personal watercraft, a steering nozzle is provided behind the water jet pump to be pivotable either to the right or to the left, and connected to a bar-type steering handle through a cable. By operating the steering handle, the steering nozzle is pivotable to the right or to the left so that a flow direction of water ejected from the water jet pump can be changed.

Japanese Patent Nos. 2756434 and 3358718 disclose a personal watercraft equipped with a reverse system configured to move the watercraft rearward. In this personal watercraft, a reverse bucket is provided behind the water jet pump to cover the steering nozzle. The reverse bucket is connected to a reverse lever mounted to a deck through a cable. By operating the reverse lever, the reverse bucket is vertically pivotable within a predetermined range.

To move the watercraft forward, the reverse bucket is held at an upper position, and the water ejected from the steering nozzle is directed substantially rearward. As the resulting reaction, the watercraft is propelled forward. On the other hand, to move the watercraft rearward, the reverse bucket is held at a lower position, and the water ejected from the steering nozzle collides with an inner wall of the reverse bucket and thereby directed substantially forward. As the resulting reaction, the watercraft is propelled rearward.

In the above described reverse system, it is necessary to temporarily hold the reverse bucket at the upper position or the lower position. Specifically, when the watercraft is traveling forward, it is necessary to hold the reverse bucket at the upper position so as not to interfere with the water ejected rearward from the steering nozzle, while when the watercraft is traveling rearward, it is necessary to hold the reverse bucket at the lower position to cause the water ejected from the steering nozzle to collide with the inner wall of the reverse bucket and to be thereby directed substantially forward.

In order to reliably hold the reverse bucket at the upper or lower position, the reverse system is typically equipped with a stopper device. The stopper device is constructed by assembling numerous parts, and has a relatively intricate structure. Such a stopper device is expensive because of the numerous parts, and may make it difficult to hold the reverse bucket at the upper or lower position with high positioning precision.

SUMMARY OF THE INVENTION

The present invention addresses the above described condition, and an object of the present invention is to provide a reverse system capable of holding a reverse bucket with a relatively simple structure and with high positioning precision.

According to the present invention, there is provided a reverse system of a water-jet propulsion personal watercraft, comprising a water jet pump configured to propel the watercraft; a reverse bucket disposed rearward of the water jet pump to be vertically pivotable and configured to receive water ejected rearward from the water jet pump and to direct the water substantially forward; and a pump cover configured to cover the water jet pump from below, wherein the pump cover includes a restricting portion, and the reverse bucket includes a stopper, the restricting portion and the stopper being configured to contact each other to restrict upward pivot movement or downward pivot movement of the reverse bucket within a predetermined range.

In this construction, the stopper of the reverse bucket and the restricting portion of the pump cover can restrict the upward pivot movement or the downward pivot movement of the reverse bucket within a predetermined range. Such a simple construction can improve positioning precision of the reverse bucket.

The pump cover may further include a mounting portion configured to pivotally mount the reverse bucket. By reducing the number of parts, a simple construction is achieved. Also, the restricting portion may be integral with the mounting portion. Because the mounting portion for the reverse bucket may serve as the restricting portion, a simpler construction is achieved.

The reverse bucket may have a substantially bowl-shaped base portion, the mounting portion may include mounting portions vertically provided on an upper surface of the pump cover to be located at right and left positions inward of the base portion of the reverse bucket, and the stopper of the reverse bucket may be configured to protrude inward from an inner wall of the base portion.

The pump cover may have a mounting portion configured to pivotally mount the reverse bucket, and the reverse bucket may be pivotally mounted by the mounting portion at a position lower than substantially a center line of a flow cross-sectional area of water ejected from the waterjet pump.

With the reverse bucket pivoted downward to a lower position, the water ejected from the water jet pump collides with the inner wall of the reverse bucket above the position at which the reverse bucket is pivotally mounted, and the resulting downward moment acts on the reverse bucket. Therefore, when the reverse bucket is pivoted downward to a lower position to move the watercraft rearward, the downward moment acts to inhibit the upward pivot movement of the reverse bucket. Consequently, the reverse bucket is stably held at the lower position.

The reverse bucket may include a substantially bowl-shaped base portion, and a flange portion configured to extend outward and rearward in a longitudinal direction of the body from a rear end of the base portion, and the flange portion may be coupled to the base portion to form an angle (reflex angle) larger than 180 degrees between an inner wall of the flange portion and an inner wall of the base portion.

In this personal watercraft, if the reverse bucket is pivoted downward while the watercraft is traveling forward with the reverse bucket held at an upper position, the water ejected from the water jet pump collides with the flange portion, which is thereby subjected to an upward external force. Therefore, the reverse bucket can be held at the upper position during the forward travel of the watercraft.

The above and further objects and features of the invention will more fully be apparent from following detailed description with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a personal watercraft according to an embodiment of the present invention;

FIG. 2 is a plan view of the personal watercraft in FIG. 1;

FIG. 3 is a rear view of the personal watercraft in FIG. 1;

FIG. 4 is an enlarged side cross-sectional view showing a rear portion of a water jet pump in FIG. 1;

FIG. 5 is a perspective view of a reverse bucket in FIG. 4;

FIG. 6A is a side view of the reverse bucket in FIG. 5;

FIG. 6B is a cross-sectional view of the reverse bucket taken along line VIb-VIb in FIG. 5;

FIG. 7 is an enlarged side view of a rear portion of the water jet pump, a part of which is illustrated in cross-section, showing a reverse system of the watercraft in FIG. 1 traveling rearward; and

FIG. 8 is an enlarged side view of the rear portion of the water jet pump, a part of which is illustrated in cross-section, showing the reverse system of the watercraft in FIG. 1 traveling forward.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a reverse system of a water-jet propulsion personal watercraft according to an embodiment of the present invention will be described with reference to drawings. The personal watercraft in FIG. 1 is a straddle-type personal watercraft equipped with a straddle-type seat 7 configured to be straddled by a rider. A body 1 of the watercraft is formed by a hull 2 and a deck 3 covering the hull 2 from above. A line at which the hull 2 and the deck 3 are connected over the entire perimeter thereof is called a gunnel line 4. The gunnel line 4 is located above a waterline 5 of the personal watercraft being at rest on the water. Herein, directions are described as seen from the perspective of the rider straddling the seat 7, and looking ahead over the bow of the watercraft. The term “longitudinal direction” is used to refer to an orientation extending from bow to stem of the watercraft, while the term “lateral direction” is used to refer to an orientation extending from starboard to port of the watercraft.

As shown in FIG. 2, a deck opening 6, which has a substantially rectangular shape seen from above, is formed on an upper portion of the body 1 at substantially a center section of the deck 3 in the longitudinal and lateral directions of the body 1 to extend in the longitudinal direction of the body 1. The straddle-type seat 7 is removably mounted over the deck opening 6 and configured to be straddled by the rider.

An engine room 8 is formed by a space defined by the hull 2 and the deck 3 below the deck opening 6. An engine E is accommodated within the engine room 8 and configured to drive the watercraft. The engine room 8 has a convex-shaped transverse cross-section and is configured such that its upper portion is smaller than its lower portion. The engine E is accommodated within the engine room 8 such that a crankshaft 9 extends along the longitudinal direction of the body 1 as shown in FIG. 1.

An output end of the crankshaft 9 is rotatably and integrally coupled with a pump shaft 11 of a water jet pump P disposed at a rear portion of the body 1 through a drive shaft 10. An impeller 12 is attached on the pump shaft 11 of the water jet pump P. Fairing vanes 13 are provided behind the impeller 12. The impeller 12 is covered with a pump casing 14 on the outer periphery thereof.

A water intake 15 is provided on the bottom of the body 1. The water intake 15 is connected to the pump casing 14 through a water passage. The pump casing 14 is connected to the pump nozzle 16 provided at the rear portion of the body 1. The pump nozzle 16 has a cross-sectional area of flow that is gradually reduced rearward. As shown in FIG. 3, an outlet port 17 is formed at a rear end of the pump nozzle 16.

The water jet pump P pressurizes and accelerates the water sucked from the water intake 15, and the fairing vanes 13 guide the water. The pressurized and accelerated water is discharged rearward through the pump nozzle 16 and from the outlet port 17, and as the resulting reaction, the watercraft obtains a propulsion force.

A bar-type steering handle 19 is attached to a front portion of the deck 3. The steering handle 19 is connected to the steering nozzle 20 (see FIG. 3) disposed behind the pump nozzle 16 through a cable (not shown). By operating the steering handle 19 clockwise or counterclockwise, the steering nozzle 20 is pivoted clockwise or counterclockwise. By operating the steering handle 19, the direction of the water ejected outside through the pump nozzle 16 is changed, and the turning direction of the watercraft is changed, while the water jet pump P is generating the propulsion force.

FIG. 4 is an enlarged side view of the rear portion of the waterjet pump P. As shown in FIG. 4, a substantially bowl shaped reverse bucket 22 is positioned behind and above the steering nozzle 20. A pump cover 23 is provided on a lower surface of the body 1 under the pump casing 14 to cover the pump casing 14 from below. Mounting portions (pivot portions) 25 are vertically provided on an upper surface of a rear portion of the pump cover 23 to allow the reverse bucket 22 to be pivotable around pivot shafts 24. As shown in FIG. 3, the mounting portions 25 are located on right and left positions inward of a base portion (indicated by reference numeral 30 in FIG. 5) of the reverse bucket 22. The left mounting portion 25 is shown in FIG. 4. As shown in FIG. 4, one end of the cable 26 is connected to the reverse bucket 22 at a position upwardly distant from the pivot shaft 24 and the other end thereof is connected to a reverse lever 27 attached to the deck 3 in the vicinity of the handle bar 19 as shown-in FIG. 1.

By operating the reverse lever 27, the reverse bucket 22 is vertically pivotable around the pivot shafts 24 provided in the mounting portions 25 of the pump cover 23 as shown in FIG. 4. When the reverse bucket 22 is pivoted downward to a lower position around the pivot shafts 24 to be positioned behind the steering nozzle 20, the water ejected rearward from the steering nozzle 20 collides with an inner wall 30A (see FIG. 6B) of the base portion 30 of the reverse bucket 22 and is directed substantially forward. Thereby, the watercraft is propelled rearward. In FIG. 4, a center line 28 of a flow cross-sectional area of the water ejected from the steering nozzle 20 is represented by a dashed line.

With reference to FIGS. 5, 6A, and 6B, a structure of the reverse bucket 22 will be described in detail. As shown in FIGS. 5 and 6A, the inner wall 30A of the base portion 30 of the reverse bucket 22 is substantially bowl-shaped and a number of ribs 31 are arranged in the longitudinal direction of the body 1 on an outer wall of the base portion 30 to extend in the lateral direction of the body 1. The reverse bucket 22 is made of synthetic resin. The ribs 31 provide rigidity to the reverse bucket 22. It will be appreciated that ribs 31 may be omitted, for example, if the reverse bucket 22 is made of a rigid material sufficient to avoid performance degrading deformation during use.

Shaft holes 32 are formed on side portions of the base portion 30 to allow the pivot shafts 24 to be inserted therethrough. The reverse bucket 22 is mounted to be vertically pivotable around the pivot shafts 24 mounted in the mounting portions 25 and extending horizontally through the shaft holes 32. As shown in FIG. 5, the shaft holes 32 are provided on the base portion 30 laterally symmetrically to conform to the pivot shafts 24 provided on the right and left mounting portions 25. As shown in FIG. 6A, a cable connecting portion 33 is provided at a position upwardly spaced apart a predetermined distance from the right shaft hole 32, and the one end of the cable 26 (FIG. 4) is connected to the cable connecting portion 33. As shown in FIG. 4, with the reverse bucket 22 positioned behind the steering nozzle 20, i.e., with the reverse bucket 22 located at the lower position, the cable connecting portion 33 and the shaft holes 32 are located above and below with respect to the center line 28 of the jet flow ejected from the steering nozzle 20.

As shown in FIG. 6B, the flange portion 34 extends outward and rearward in the longitudinal direction of the body 1 from a rear end of the base portion 30. The flange portion 34 is coupled to the base portion 30 to form an angle (reflex angle) larger than 180 degrees between an inner wall 34A of the flange portion 34 and the inner wall 30A of the base portion 30.

A crank-shaped stopper 35 is vertically provided on the inner wall of the reverse bucket 22 in the vicinity of the left shaft hole 32. The stopper 35 is in contact with a restricting portion 25 a (FIG. 4) formed on an end surface of a rear portion of the mounting portion 25 formed on the pump cover 23 for mounting the reverse bucket 22, when the reverse bucket 22 is located at the upper or lower position. As shown in FIG. 4, with the reverse bucket 22 located at the lower position during the rearward travel of the watercraft, a first stopper surface 35 a of the stopper 35 is in contact with a lower portion of the restricting portion 25 a formed at the end surface of the rear portion of the left mounting portion 25, thereby restricting the downward pivot movement of the reverse bucket 22. By operating the reverse lever 27 (FIG. 1) to cause the reverse bucket 22 to be pivoted downward, the reverse bucket 22 is held at the lower position defined by the restricting portion 25 a and the stopper 35 in contact with each other.

As represented by a two-dotted line in FIG. 4, with the reverse bucket 22 located at the upper position during the forward travel of the watercraft, a second stopper surface 35 b of the stopper 35 is in contact with an upper portion of the restricting portion 25 a formed at the end surface of the rear portion of the mounting portion 25, thereby restricting the upward pivot movement of the reverse bucket 22. By operating the reverse bucket 22 (FIG. 1) to cause the cable 26 to be pulled forward, the reverse bucket 22 is pivoted upward and held at the upper position defined by the stopper 35 and the restricting portion 25 a in contact with each other. As should be appreciated, the reverse bucket 22 is vertically pivotable within a predetermined range defined by the restricting portion 25 a and the stopper 35, and is typically incapable of being pivotable outside this range. In addition, by operating the reverse lever 27, the reverse bucket 22 is held at the upper or lower position defined by the restricting portion 25 a and the stopper 35 in contact with each other.

As shown in FIG. 6B, a number of fins 40 are formed on the inner wall 30A of the base portion 30. Side fins 41 are provided on right and left sides of the inner wall 30A of the base portion 30. Two center fins 42 are provided on the inner wall 30A of the base portion 30 to be located between the side fins 41. The side fins 41 and the center fins 42 are configured to extend in substantially the longitudinal direction of the body 1. The side fins 41 and the center fins 42 are structured such that their rear portions protrude less than their front portions. In FIG. 6B, the left side fin 41 and the left center fin 42 are illustrated. The side fins 41 and the center fins 42 are provided on the inner wall 30A of the base portion 30 such that the side fins 41 are laterally symmetric and the center fins 42 are laterally symmetric.

FIG. 7 is an enlarged side view of the rear portion of the waterjet pump P, a part of which is illustrated in cross-section, showing the reverse system of the watercraft traveling rearward. As shown in FIG. 7, to move the watercraft rearward, the reverse lever 27 (FIG. 1) is operated to cause the reverse bucket 22 to be pivoted downward around the pivot shafts 24. The water ejected from the steering nozzle 20 collides with the inner wall 30A of the reverse bucket 22 and is directed substantially forward, thus generating a propulsion force for moving the watercraft rearward.

The water colliding with the inner wall 30A of the base portion 30 and directed substantially forward is controlled by the side fins 41 and the center fins 42. Consequently, the water ejected from the steering nozzle 20 is smoothly directed substantially straight forward by inhibiting the water from being scattered to the right or to the left. Therefore, the propulsion force generated in the water jet pump P is efficiently changed into the propulsion force for moving the watercraft rearward.

Since the shaft holes 32 of the reverse bucket 22 are located lower than the center line 28 of the water flow ejected from the steering nozzle 20, which substantially conforms to a center line of the steering nozzle 20 in a horizontal direction, a downward moment acts on the reverse bucket 22 when the water ejected from the steering nozzle 20 collides with the reverse bucket 22 during the rearward travel. When the reverse bucket 22 is located at the lower position and receiving the water ejected from the steering nozzle 20, it is stably held at the lower position by the downward moment, the restricting portion 25 a and the stopper 35 for restricting the downward pivot movement.

FIG. 8 is an enlarged side view of the rear portion of the waterjet pump P, a part of which is illustrated in cross-section, showing the reverse system of the watercraft traveling forward. As described previously, by operating the reverse lever 27 (FIG. 1) to cause the cable 26 to be pulled forward, the reverse bucket 22 is held at the upper position. As a result, the water from the steering nozzle 20 is ejected rearward without colliding with the inner wall 30A of the reverse bucket 22 and thereby being directed substantially forward, thereby generating the propulsion force for moving the watercraft forward.

Here it is assumed that the reverse bucket 22 is pivoted slightly downward when the watercraft is traveling forward. In this case, as shown in FIG. 8, the water ejected from the steering nozzle 20 collides with the inner wall 34A of the flange portion 34 of the reverse bucket 22. As the resulting reaction, a lifting force is applied to the reverse bucket 22. When the reverse bucket 22 is in a position that is pivoted slightly downward when the watercraft is traveling forward, the reverse bucket is urged upward by the lifting force generated by the collision of the water with the flange portion 34. So, the reverse bucket 22 is stably held at the upper position.

In accordance with the reverse system constructed as described above, the reverse bucket 22 is stably held at the upper or lower position with a simple construction, i.e., by the restricting portion 25 a and the stopper 35. Specifically, since the shaft holes 32 are located lower than the center line 28 of the water flow ejected from the steering nozzle 20, the reverse bucket 22 is stably held at the lower position during the rearward travel, while the reverse bucket 22 is stably held at the upper position because of the flange portion 34 during the forward travel. Such a simple construction can enhance precision with which the reverse bucket 22 is positioned at the upper or lower position.

While the reverse bucket 22 is pivotally mounted by the mounting portions 25 and a pivot movement range of the reverse bucket 22 is restricted by the restricting portions 25 a, which are integral with the mounting portions 25, as well as by the stopper 35, the restricting portion for restricting the pivot movement range and the mounting portion for mounting the reverse bucket may alternatively be separately provided.

As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims. 

1. A reverse system of a water-jet propulsion personal watercraft, comprising: a water jet pump configured to propel the watercraft; a reverse bucket disposed rearward of the water jet pump to be vertically pivotable and configured to receive water ejected rearward from the water jet pump and to direct the water substantially forward; and a pump cover configured to cover the water jet pump from below, wherein the pump cover includes a restricting portion, and the reverse bucket includes a stopper, the restricting portion and the stopper being configured to contact each other to restrict upward pivot movement or downward pivot movement of the reverse bucket within a predetermined range.
 2. The reverse system of a water-jet propulsion personal watercraft according to claim 1, wherein the pump cover further includes a mounting portion to which the reverse bucket is pivotally mounted.
 3. The reverse system of a water-jet propulsion personal watercraft according to claim 2, wherein the restricting portion is integral with the mounting portion.
 4. The reverse system of a water-jet propulsion personal watercraft according to claim 3, wherein the reverse bucket has a substantially bowl-shaped base portion, the mounting portion includes mounting portions vertically provided on an upper surface of the pump cover to be located at right and left positions inward of the base portion of the reverse bucket, and the stopper of the reverse bucket is configured to protrude inward from an inner wall of the base portion.
 5. The reverse system of a water-jet propulsion personal watercraft according to claim 1, wherein the pump cover has a mounting portion configured to pivotally mount the reverse bucket, and the reverse bucket is pivotally mounted by the mounting portion at a position lower than a center line substantially at the center of a flow cross-sectional area of water ejected from the water jet pump.
 6. The reverse system of a water-jet propulsion personal watercraft according to claim 5, wherein the reverse bucket includes a substantially bowl-shaped base portion, and a flange portion configured to extend outward and rearward in a longitudinal direction of the body from a rear end of the base portion, and wherein the flange portion is coupled to the base portion to form an angle larger than 180 degrees between an inner wall of the flange portion and an inner wall of the base portion. 